Electric incandescent lamp



Sept. 10, 1940. w. H. LUND ELECTRIC INCANDESCENT LAMP Filed Nov. 2, 1939 Inventov:

fiw u n L F Ham w m H b Patented Sept. 10, 1940 ELECTRIC INCANDESCENT LAMP Wilfrid H. Lund, Beckenham, England, assignor to General Electric Company, a. corporation of New York Application November 2, 1939, Serial No. 302,613

In Great Britain October 6, 193a 6 Claims.

My invention relates to electric incandescent lamps and more particularly to lamps such as are used in the headlights of self propelled vehicles.

Many types of lamps have hitherto been proposed for automotive headlighting purposes. Among these is one in which a filament of U or semicircular form is arranged in a bulb at right angles to the axis thereof so that when the lamp is mounted in a reflector, the U is upright and the lowermost part or base of the U lies approximately on .the longitudinal axis of the lamp. Such a lamp gives a flat topped beam in which none of the light rays are reflected upwards .but are spread sufiiciently sideways to give effective illumination of the road surface. In order to increase the illumination in an upward direction it has been proposed to add to a lamp with the above type of filament a second substantially V-shaped filament, the limbs of the V lying substantially in the horizontal plane containing the axis of the lamp and the apex of the V lying in close proximity to the lowermost part of the U- shaped filament. This V-shaped filament illuminates the road for a longer distance than the U-shaped filament, and should be cut out of circuit and the U-shaped filament connected in circuit, when the vehicle is approaching an oncoming vehicle, so as not to dazzle the driver of the on-coming vehicle.

An object of the present invention is to increase the usefulness of such double filament lamps, and to that end it consists in adding a third filament mounted above the horizontal plane containing the axis of the lamp so that the 5 light from it will be substantially all reflected downwards and will give an illumination suitable for driving in a fog.

Further objects and advantages of my invention will appear from the following description 40 and from the accompanying drawing in which Fig. l is a perspective view of an electric incandescent lamp comprising my invention; Fig. 2.

is a diagrammatic front view of the lamp shown in Fig. 1; Figs. 3 and 4 are diagrammatic front 45 views of two modifications of the invention; Fig.

5 is a diagrammatic side view of another modification of my invention with the lamp shown mounted in position within a reflector; Fig. 6

is a diagrammatic front view of the lamp shown 5 in Fig. 5; and Figs. '7 and. 8 are diagrammatic front views. of two further modifications of my invention. i j

Referring to the drawing, the, lamp there shown comprises a bulb l0 having a'base Ii se- 55 cured thereto. Mounted within. the bulb are three filaments l2, l3 and H which are connected by leading-in wires l5, I6, l1 and It! to the contacts on the base, leading-in wire l8 being common to all three filaments. The filaments consist of a single or multiple coil of tungsten or 5 other suitable refractory metal. The lamp. is

- adapted to be mounted in a light concentrating,

preferably parabolic, reflector l9 so that the longitudinal axis a--a of the lamp coincides with the axis rr of the reflector, as shown in Fig. 5. Filament I2 is formed into a U-shape with the plane of the legs or limbs of the U extending transversely to the lamp axis a-a. This U-shaped filament I2 is so arranged within the bulb II) that when the lamp is mounted in a reflector I9, the said filament will lie substantially in the focal plane f-f of such reflector (Fig. 5) with the limbs of the U extending vertically upwards and the base of the U substantially coinciding with the focal point F of the reflector. 0 In accordance with accepted practice, the focal plane .f-f of the reflector is that plane passing through the focal point F of the reflector at right angles to the axis rr thereof. In such position, the U-shaped filament i2 is symmetrically dis- 25 posed about the vertical axial plane 0-12 of the reflector.

The second filament I3 is of V-shape and is so arranged within the bulb l0 that the limbs of the V lie substantially in the horizontal plane con- 30 taining the axis r-r of the reflector with the apex of the V lying in close proximity to the lowermost part of the U-shaped filament (and hence to the reflector focal point), and with the limbs of the V extending rearwardly so as to be symmetrically disposed about the reflector axis 1-1.

-In accordance with the invention, the third filament I4 is mounted within the bulb In so as to lie substantially in the focal plane ff of the reflector I9 and be disposed entirely above the horizontal plane hh containing the axis r-r of such'reflector. This third filament I4 may be substantially straight or it may be of U or V-shape.

When the third filament I4 is straight, it may be mounted so as to extend vertically and lie on either the right or the left side of the U-shaped filament l2, as shown in Figs. 2 and 3 respectively, with its lower end located approximately in the horizontal plane h-h containing the axis rr of the reflector and with its length substantially parallel to the straight portion of the limbs of the U-shaped filament l2. Alternatively, the straight-third filament l4 may be arranged vertically between the limbs of the U-shaped filament II with its lower end slightly spaced from the base portion of such filament II, as shown in Fig. 4; or it may be arranged horizontally above the U-shaped filament as indicated in Figs. 5 and 6. In the latter case, the horizontally arranged filament ll may be located symmetrically with respect to the vertical axial plane v--v of the reflector or to one side or the other of said plane.

As stated before, the third filament I l in each of the above arrangements is mounted so as to lie substantially in the plane of the U-shaped filament l2, which corresponds to the focal plane 1-1 of the reflector l9.

When the third filament, instead of being straight, is made of U or V-shape, as indicated at 20 in Figs. 7 and 8, it is preferably arranged in the same plane as that of the main U-shaped filament l2 with its limbs inverted with respect to the said main U-shaped filament. One limb of the inverted. U or V shaped filament 20 is arranged between the limbs of the main U-shapedfilament I 2, while the other limb of such filament 2D is arranged on either the right or left side of the main U-shaped filament If, as shown in Figs. '7 and 8 respectively. In this manner, the limbs of the main U-shaped filament l2 and the U or v-shaped third filament 20 are more or less interleaved.

As previously stated, one end of each of the three filaments l2, I3 and I4 or 20 is connected by leading-in wires I5, I 6 and II, respectively, to separate contacts on the base H of the lamp, while their other ends are all connected by a common leading-in wire l8 to a fourth and common contact on the base. A four position switch may be employed to control the supply of current to the various filaments.

In one of the positions of the switch, the straight or U-shaped third filament H or 20 is connected in circuit. As only the lower end of this filament, in any of the various arrangements described hereinabove, is in proximity to the focus of the reflector, and the remainder is entirely above the reflector axis, practically all the light will be projected downwardly to give a suitable dip or fog beam.

In a second position, the switch connects the main U-shaped filament l2 in circuit so as to give a non-dazzling beam such as called for by the motor regulations.

In a third position, the switch connects the supply of current to the V-shaped horizontal filament so that the lamp will give its maximum illumination in the form of a high beam extending far down the road.

In order to further improve the non-dazzle and fog driving characteristics of the headlamp when a straight third filament I4 is used, this filament may have a cup or other suitably shaped supplementary reflector mounted in front of it to prevent direct non-reflected light rays from leaving the lamp and so causing a nimbus of lighted-up fog particles, all the direct rays being reflected back onto the parabolic reflector I9 of the headlamp. Alternatively, the inner surface of the supplementary reflector may be roughened or made matte to prevent re-refiection, if so desired.

When the third filament is arranged to one side or the other of the main U-shaped filament l2, it,will cast a beam to the side of the vehicle opposite to that side on which the filament is mounted. Such a beam is adapted to be thrown to the near side of the road where it will illuminate the curb and facilitate driving in foggy weather.

In place of a separate incandescent lamp and reflector, the filaments may, of course, be incorporated in a unitary reflector lamp of the type disclosed in Patent 2,148,314, D. K. Wright, which is assigned to the assignee of the present invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a vehicle headlamp, the combination of a light-concentrating reflector provided with three independently energizable filaments comprising a main U-shaped filament disposed in the focal plane of said reflector with the base of the U located substantially at the focal point of said reflector and the limbs of the U extending vertically upward, a V-shaped filament disposed substantially in the horizontal plane including the axis of said reflector with the apex of the V disposed closely adjacent the focal point of said reflector and with the limbs of the V extending rearwardly and symmetrically about the reflector axis, and a third filament arranged in the focal plane of said reflector and disposed entirely above the horizontal axial plane of said reflector.

2. In a vehicle headlamp, the combination of alight-concentrating reflector provided with three separately energizable filaments comprising a main U-shaped filament disposed in the focal plane-of said reflector with the base of the U located substantially at the focal point of said reflector and the limbs of the U extending vertically upward, a V-shaped filament disposed substantially in the horizontal plane including the axis of said reflector with the apex of the V disposed closely adjacent the focal point of said reflector and with the limbs of the V extending rearwardly and symmetrically about the reflector axis, and a straight filament arranged vertically in the focal plane of said reflector and disposed entirely above the horizontal axial plane of said reflector.

3. In a vehicle headlamp, the combination of a light-concentrating reflector provided with three separately energizable filaments comprising a main U-shaped filament disposed in the focal plane of said reflector with the base of the U located substantially at the focal point of said reflector and the limbs of the U extending vertically upward, a V-shaped filament disposed substantially in the horizontal plane including the axis of said reflector with the apex of the V disposed closely adjacent the focal point of said reflector and with the limbs of the V extending rearwardly and symmetrically about the reflector axis, and a straight filament arranged vertically in the focal plane of said reflector and disposed entirely above the horizontal axial plane of said reflector and to one side of said main U-shaped filament.

4. In a vehicle headlamp, the combination of a light-concentrating reflector provided with three separately energizable filaments comprising a main U-shaped filament disposed in the focal plane of said reflector with the base of the U located substantially at the focal point of said reflector and the limbs of the U extending vertically upward, a V-shaped filament disposed substantially in the horizontal plane including the axis of said reflector with the apex of the V disposed closely adjacent the focal point of said reflector and with the limbs of the V extending rearwardly and symmetrically about the reflector axis, and a straight filament arranged vertically in the focal plane of said reflector and disposed entirely above the horizontal axial plane of said reflector and between the limbs 01' said main U-shaped filament.

5. In a vehicle headlamp, the combination of a light-concentrating reflector provided with three separately energizable filaments comprising a main U-shaped filament disposed in the focal plane of said reflector with the base of the U located substantially at the focal point of said reflector and the limbs of the U extending vertically upward, a V-shaped filament disposed sub stantially in the horizontal plane including the axis of said reflector with the apex of the V disposed closely adjacent the focal point of said reflector and with the limbs of the V extending rearwardly and symmetrically about the reflector axis, and a second U-shaped filament arranged in an inverted position in the focal plane of said reflector and entirely above the horizontal axial :0 plane thereof with one of its limbs disposed between the limbs 01' said main U-shaped filament and the other of its limbs disposed to one side of said main U-shaped filament.

6. An electric incandescent lamp for vehicle headlamps comprising a glass bulb, and three independently energizable filaments sealed within said bulb and comprising a main U-shaped filamerit disposed in a plane extending transversely of the lamp axis with the base of the U located substantially in the lamp axis and the limbs of the U extending vertically upward, a V-shaped filament disposed substantially in the horizontal axial plane of said lamp with the apex of the V disposed closely adjacent the base of said U- shaped filament and with the limbs of the'v extending rearwardly of said bulb and sym metrically about the lamp axis, and a third filament arranged in the plane of said U-shaped filament and disposed entirely above the horizontal axial plane of said lamp.

WJLFRID H. LUND. 

